The pain first came during my first class of aerobics, I was doing a squat and I felt pressure and pain on my left knee on my way back up from the squat. I stretched properly beforehand and cooled down afterwards too so I don t know what could have caused it. Back at home I also noticed that when I would pick something up it would hurt too(like getting into a squat position and getting something). Once I get into a fully standing position my knee pops like when I pop my fingers.